Hi there! This is a game i played on one of those classic arcade
machines in the early/mid nineties. You know, those lovely black
ones, or, did they look like that in sweden only? ... Aaanyway...

As i remember this game, it looked a little like Ghost'n'Goblins/Ghouls 'n' Ghosts...
It had something to do with a castle, and i vagely remember some
level with a fire/lava.. but the thing i remember most is a level,
with round saw blades that moved left/right, on the ground and
in the ceiling... i think it was some kind of mad professor that was
the evil dude...

And yea.. a somewhat medieval feeling...

does this ring a bell for someone? this is making me crazy!
and remember, i played it on the arcades, but... who knows,
an amiga version might exist?... hmm...

I remember a C64 game called Dragon's kingdom (I think that was the name of it) which played almost exactly like ghosts n goblins/ghouls n ghosts and had a lava world as the 4th world. I was really really happy with the infinite lives trainer on that one.

There's a screenshot of it on lemon64.com. Might need to just search for kingdom.

Your description somehow reminds me of an arcade game called Wardner which is published in 1988. It is a horizontal scrolling platform game starring a guy who must rescue his girlfriend who has turned into a crystal ball.
The second level in this game is set in a huge factory with moving Acme blades.

OMG!!! That game looks exactly like the arcade game I saw when I was younger just before we got a disk drive for our C64. I remember buying Montezuma's revenge (first disk game I had) because the character there reminded me slightly of a C64 looking version of the character in that game.

I was awake for some hours last night trying to recall more
from the game, to write here.. but i had really lost hope!
My poor description of the game and all..
I am checking out Wardner.. will be back here soon, hopefully
with tears in my eyes. =)

If you want to see more screenshots of Wardner, visit KLOV.com for screenshots of the Japanese version.

The first time I saw this game was in multiformat mag 'The GamesMachine' in 1988. They reviewed this arcade-game and promised a conversion to Amiga would soon appear. Pity it never happened.
I have the game in Mame (downloaded from Planetemu.net) and it looks, feels and plays like an Amiga game! It has some parallax scrolling backgrounds and great music. I still haven't finished it (despite shoveling in zillions of virtual coins).

The picture below is taken from the intro screen in which the boy and girl are enchanted to take a trip into a magic forest.

Mr Wardner looks like an old wizard.. after he has taken some
hits he transforms into a huge uggly monster of some kind..
The ending was a great dissapointment..
The hero and the princess holds hands and jumps up and down,
and a "Congratulations!" text is displayed.. nothing else.. =)

The moving spikes?... Those are ease, took me two retries,
the hard part is right before Mr Wardner...